Purification of steroids



nited States rUmrrcArroN or sTEuorns No Drawing. Application November 17, 1953 SerialNo. 392,767

8. Claims. (Cl. 260--397.4)

This invention relates to the purification ofsteroids; and it has for. its object. the provisionof an advantageous method of separatingcertain steroids from genetic contaminants, as well as the provision of valuable products derived from these steroids.

[The compounds M-pregnene-llfldh, 21-triol-3,20- dione and its lla-epimer will for, convenience be referred to herein as F and. epi Ff respectively.]

In the production of epi F by microbiological oxidation [cf. 1. Am. ,Chem. Soc., 74, 3962 (1952); U. S. patentapplication Serial No. 296,256, filed June 28, 1952], the product. is obtained in colored impure form. It has been. found that the epi F in the product can readily be separated from its genetic (colored) coutaminants simply by converting the epi. F into its chloroform adduct, recovering this adduct, and treating the adduct to obtain free epi F; and it has also been found that a number of related steroids can be converted into relatively stable adducts with various halo-alkanes, which adducts are similarly useful in the separation of the steroids from contaminants and for other purposes.

The adducts of the invention may be solvate com plexes or embody halo-alkane of crystallization; but it is. not intended that the invention be limited by any theoretical explanation. By virtue of their low solubility in. the halo-alkane solvent (e. g. chloroform), crystallinity, substantially-quantitative formation, and relatively high stability to heat and/or vacuum (some being stable up to 0.5 mm. at 1005 C.), production of'these adducts provides a simple and efiicient means of purifying the particular steroids.

The steroids foundto form. such adducts are F, epi F, epi F 11,21-diacetate, and n -pregnadiene-3,8-ol--one. The first three form adducts containing one mole haloalkane/mole steroid, whereas the last forms. an adduct containing one mole halo-alkane/two, moles steroid. ,The

preferred steroids for the purposes of this invention are.

the M-pregnene-l1,17u,2l-triol-3,20-diones (i. e. F. and epi F).

The halo-alkanes. utilizable for the purposes of the invention are preferably relatively low-boiling chloro and bromo derivatives of methane and ethane, inter alia chloroform, bromo-form, methylene chloride, ethylene dichloride and sym. tetrachloroethane.

The adducts of this invention are formed on dissolving the steroid in the halo-alkane and reducing the dissolving power of the halo-alkane (e. g. by cooling the solution or removing solvent by evaporation). Preferably, the steroid is first at least partially purified to a crudeon semi-crystalline state. Alternatively (but less desirably), the adduct may be obtained by merely washing the steroid with the halo-alkane. If production of the adduct per se is the object, the starting material may of course be the pure steroid. I

The (purified) free steroid may be obtained from the adduct by treatment with a different organic solvent for the steroid (i. e. a solvent other than an adduct-forming atent "ice halo-alkane). Thus, the free steroid may be obtained by dissolving, the choloroform adduct in methanol, and removing chloroform and methanol by evaporation (the binary. system 12.5% methanol and 87.5% chloroform evaporating at 5 3.6 C.).. Alternatively, where the adduct is relatively labile, to. heat and vacuum, it may be con: verted to the free steroid by such treatment.

The following examples are. illustrative of the invention:

Example 1 (a) 500 mg. crude crystalline epi F [obtained, for example, by microbiological oxidation of 11-desoxy-17- hydroxy-corticosterone with Aspergillus niger, filtering the I culture, extracting the. filtrate with a substantially waterimmiscible organic solvent for epi F, and removing the solvent by evaporation in vacuo] is dissolved in 200 ml. warm chloroform; and the crystals formed on cooling are recovered by filtration. The adduct thus obtained has the. following. properties: Colorless platelets. M. P., about 206-9. C. [a] +88j- 2 (0.5% in ethanol), +87.8. being the. calculated: specific rotation for an adduct containing one mole of chloroform. Analysis, after drying in vacuo (1 mm. Hg) at C. for two hours: C, about 54.92; H, about 6.59; and Cl, about 21.99 (calculatedfor C H O CHCl: C, 54.83; H, 6.49; and Cl, 22.08). Theinfr ared spectrum, sampled as Nujol mull, differs from that of free epi F in that it contains a deepbandat 13.28 ,u, characteristic for chloroform; moreover, the C -carbonyl band shifts from 5.83 a for the free steroid to 5.88 forthe adduct.

(b) 664 mg, of the, adduct obtained in a is dissolved in 50 ml. methanol, and the methanol removed with chloroform by. evaporation at about 536 C. The residue is colorless crystalline free epi F.

Among. the other organic solvents utilizable for conversion of the adduct to free epi F are other lower aliphatic alcohols (e. g. ethanol), acetone, ethyl .acetate, and mixtures thereof.

' Example 2 The 11,21-diacetate of'epi F (i. e. A -pregnene-lla,l7ot, 21-triol-3,20-dione 11,21-diacetate) is treated as described in section a of Example 1 to obtain its chloroform A -pregnadiene-3 8-01-20-one is treated as described in section a of Example 1 to obtain a chloroform adduct (in which one mole of chloroform is associated with two moles of the steroid), having the following properties: Colorless platelets. Stable to vacuo (1 mm.), but labile to heat. M. P., same as that of the free steroid. [a] 20:2 (0.5% in ethanol), differing as expected, by 19% from that of the free steroid. Analysis: C about 69.27; H, about 8.34; and Cl, about 14.21 (calculated for (1 1-1 0 /2. CHCI I C, 69.02; H, 8.22; and Cl, 14.22). The adduct shows a strong band at 13.32 a, characteristic for chloroform, and three additional bands at 10.54, 11.78 and 11.99 ,u; the C -carbonyl band shifts from 6.05 to 6.02 y. for the adduct, and four minor bands of the free steroid (8.62, 10.45, 12.41 and 12.52 a) appear at slightly lower wave lengths for the adduct; and the band at 9.86 p. is missing for the adduct.

The adduct may be converted to the free steroid as described in section b of Example 1.

Example 4 321.6 mg. compound F [hydrocortisone] (preferably crystalline) is dissolved in ml. Warm chloroform; and the crystals formed on cooling are recovered by filtration.

The adduct thus obtained has the following properties: Elongated flat needles which show birefringence. M. P., about 2047 C. [a] +129.2 (0.5 in ethanol), +l27.2 being the calculated specific rotation for a 32.9% increase in molecular weight. The adduct is stable to vacuum but relatively labile to heat and to combined vacuum and heat (1 mm. Hg, 100 C.). Its analysis is: C, about 54.8%; H, about 6.5%; and Cl, about 22% (analysis compound F: C, 69.58%; and H, 8.34%). The infrared spectrum shows the band typical for chloroform, and in addition the following changes:

Compound F: Chloroform adduct:

7.82 ms 7.87 sh 8.33 ms 8.33 h 9.10 sh 9.10 s 9.73 w 9.71 sh If desired, the adduct may be converted to free (purified) compound F by crystallizing from a lower aliphatic alcohol, acetone, ethyl acetate, or mixtures thereof; or, alternatively, it may be heated to about 100 C. under vacuum to free the steroid.

Example 5 237.7 mg. crystalline compound F is dissolved in 250 ml. hot ethylene dichloride; and the solution (which turns slightly brownish on heating) is evaporated to dryness, and the residue dried for 12-16 hours at room temperature under high vacuum. The increase in weight of the compound F corresponds well with that calculated for one mole ethylene dichloride. The adduct is relatively labile to combined heat (about 100 C.) and vacuum, and may be decomposed by such treatment to obtain free compound F.

The difference between the chloroform adducts of F and epi F in their lability to heat (and especially combined heat and vacuum) may be employed as a basis for a method of determining the amounts of these steroids in a mixture of the two, or for a method of separating F from epi F (using, for example, 100 C. and 1 mm. Hg vacuum).

Example 6 407.1 mg. epi F is dissolved in 250 ml. methylene chloride, and the solution is evaporated to dryness by means of a stream of air. The weight increase corresponds well for that calculated for one mole methylene chloride. The adduct is stable under high vacuum at room temperature.

Example 7 Employing ethylene dichloride in place of the methylene chloride in Example 6 yields a product whose weight increase corresponds well with that calculated for a monomolecular epi F-ethylene dichloride adduct.

Example 8 may be recovered by subjecting the adduct to high vacuum at C.

Example 9 26 mg. compound F is dissolved in an excess of freshlydistilled bromoform, and the solution is evaporated to dryness, yielding a product whose. weight increase corresponds well with a mono-molecular adduct.

Example 10 373 mg. compound F is dissolved in ml. sym. tetrachloroethane, and the solution is evaporated to dryness at 3040 C. with the aid of an air jet. The weight of the product corresponds well with that calculated for a mono-molecular adduct. It is stable to vacuum.

The adducts of this invention may be employed in place of the free steroid for various purposes. Thus, the chloroform adduct of epi F (cf. Example 1a) may be employed in place of free epi F in the conversion into cortisone acetate (e. g. as described in d alternative 2 of Example 4, application Serial No. 296,256).

The invention may be variously otherwise embodied within the scope of the appended claims.

I claim:

1. The method of separating a steroid of the group consisting of hydrocortisone, A -pregnene-11-alpha,17- alpha,21-triol-3,20-dione, A -pregnene-11-alpha,17-alpha,- 21-triol-3,20-dione 11, 21-diacetate, and A -pregnadiene- 3fl-ol-20-one from genetic contaminants, which comprises forming a halo-alkane adduct of the steroid, recovering the adduct, and treating the adduct to obtain the free steroid, the halo-alkane being a member of the group consisting of the relatively low-boiling chloro and bromo derivatives of methane and ethane.

2. The method of claim 1, in which the steroid is A pregnene-l l-alpha,17alpha,21-triol-3,20-dione produced by microbiological oxidation of 11-desoxy-17-hydroxycorticosterone.

3. The method of claim 1, in which the adduct is treated with a different organic solvent for the steroid under crystallization conditions.

4. The method of claim 1, in which the adduct is dissolved in a solvent of the group consisting of lower aliphatic alcohols, acetone, ethyl acetate, and mixtures thereof, and said solvent is removed with the halo-alkane by evaporation.

5. The method of claim 4, methanol.

6. A crystalline halo-alkane adduct of a steroid of the group consisting of hydrocortisone, A -pregnene-11- alpha,l7 alpha,21 triol 3,20 dione, M-pregnene 11- alpha,17-alpha,21-triol-3,20-dione 11,21-diacetate, and A -pregnadiene-35-ol-20-one, the haloalkane being a member of the group consisting of relatively low-boiling chloro and bromo derivatives of methane and ethane.

7. A crystalline chloroform adduct of a steroid of the group consisting of hydrocortisone, A -pregnene-11-alpha,- 17alpha,21-triol-3,20-dione and A -pregnene-11-alpha,- 17alpha,21-triol-3,20-dione 11,21-diacetate, in which the chloroform and steroid are in the molar ratio of 1:1.

8. A crystalline chloroform adduct of the steroid A -pregnadiene-3fi-ol-20-one, in which the chloroform and the steroid are in a molar ratio of 1:2.

in which the solvent is References Cited in the file of this patent UNITED STATES PATENTS 2,602,769 Murray et al. July 8, 1952 CERTIFICATE Patesnt No a 2, 849 460 F CREQTIUN August 26, 1958 I-Ielmuth Cords Patent should read as corrected below.

Column 1 line 43, for "1005 09)," read m 166 00), line 25, for "651C312" read 019161 Signed and sealed. this 11th day of November 1958,

Amest:

KARL .Z L AXLINE ROBERT C. WATSON Attesting Ofi'icer Commissioner of Patents 

1. THE METHOD OF SEPARATING A STERIOD OF THE GROUP CONSISTING OF HYDROCORTISONE, $4-PREGNENE-11-ALPHA, 17ALPHA,21-TRIOL-3,20-DIONE, $4-PREGNENE-11-ALPHA,17-ALPHA,21-TRIOL-3, 20-DIONE 11, 21-DIACETATE, AND $5,16-PREGNADIENE3B-OL-20-ONE FROM GENETIC CONTAMINANTS, WHICH COMPRISES FORMING A HALO-ALKANE ADDUCT OF THE STERIOD, RECOVERING THE ADDUCT, AND TREATING THE ADDUCT TO OBTAIN THE FREE STEROID, THE HALO-ALKANE BEING A MEMBER OF THE GROUP CONSISTING OF THE RELATIVELY LOW-BOILING CHLORO AND BROMO DERIVATIVES OF METHANE AND ETHANE. 